Align CONTRIBUTING.md with the current development setup

[forthfate]

Summary

CONTRIBUTING.md still documents an older local-development path. It lists Python 3.11+, Node 20+, npm commands, and orbit-agent-console, while the current repository uses Python 3.13+, Node 24+, pnpm, and the orbit command.

This is a documentation-only contribution with no product-code changes required.

Scope

• Update the required Python and Node.js versions to match the project configuration and README.
• Replace obsolete npm commands with the current pnpm commands.
• Replace the obsolete packaged-app command with the current orbit run command.
• Keep the development, pre-commit, and release instructions internally consistent.

Acceptance criteria

• The development instructions agree with README.md, pyproject.toml, and package.json.
• No reference to the removed orbit-agent-console command remains.
• Commands are copyable and use the repository's declared package manager.
• No production source code changes are needed.

Helpful files

• CONTRIBUTING.md
• README.md
• pyproject.toml
• package.json

Questions are welcome—please leave a comment if any command or version requirement is unclear.